In collaboration with Dr. Ronald Levy at Stanford, monoclonal antibodies were produced that could discriminate between a T-cell leukemia (T-ALL) and a B-lymphocyte cell line from the same patient (Levy, 1979). Approximately 60 hybridoma clones were isolated which produced monoclonal antibody that could be divided into the following categories: (1) antibody that binds to T-ALL but not to either B cell lines or peripheral blood lymphocytes (PBL); (2) antibody that binds to both T-ALL and PBL but not to B cells; (3) antibodies that bind to both T and B cells but immunoprecipitate different size molecules from each cell. For each class of antibodies, we have obtained preliminary data including antibody binding profiles, fluorescent staining patterns and characterization of the antigens recognized using immunoprecipitation and gel electrophoresis. We have noted that a monoclonal antibody may immunoprecipitate different molecular weight antigens from different cell types (and in disease states). To extend these results, peptide maps of immunoprecipitated antigens will be performed. We will extend our library of monoclonal antibodies to obtain additional antibodies that react with subpopulations of lymphocytes. These monoclonal antibodies will be used to classify lymphocytes into subsets based on cell surface antigens in both normal and disease states. These reagents may prove useful not only in classifying the types of lymphocytes involved in inflammatory reactions and lymphoproliferative diseases, but also may prove useful in early detection of disease relapses. An additional advantage of monoclonal antibodies is that high titers and large amounts of antibody can be produced that make it suitable for widespread use as a detecting reagent. Finally, by detecting specific antigens associated with disease states, monoclonoal antibodies can potentially play a major role in elucidating the pathogenesis of autoimmune diseases.